#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    char dismantlingAction(string arr)
    {
        unordered_map<char, int> unmap;
        for (auto& a : arr)
        {
            unmap[a]++;
        }
        for (auto& a : arr)
        {
            if (unmap[a] == 1)
            {
                return unmap.find(a)->first;
            }
        }
        return ' ';
    }
};